Air and fluid cooling of a data center

ABSTRACT

An apparatus is provided herein. The apparatus includes a sensor module and a control module. The sensor module to receive a measured environmental condition. The control module to use the measured environmental condition to determine a fluid temperature to cool a first set of components and determine an air temperature to cool a second set of components.

BACKGROUND

Electronic devices have temperature requirements. Heat from the use ofthe electronic devices is controlled using cooling systems. Examples ofcooling systems include air and liquid cooling.

BRIEF DESCRIPTION OF THE DRAWINGS

Non-limiting examples of the present disclosure are described in thefollowing description, read with reference to the figures attachedhereto and do not limit the scope of the claims. In the figures,identical and similar structures, elements or parts thereof that appearin more than one figure are generally labeled with the same or similarreferences in the figures in which they appear. Dimensions of componentsand features illustrated in the figures are chosen primarily forconvenience and clarity of presentation and are not necessarily toscale. Referring to the attached figures:

FIG. 1 illustrates a block diagram of a system according to an example;

FIGS. 2-4 illustrate the system of FIG. 1 according to examples;

FIG. 5 illustrates a block diagram of a control apparatus according toan example;

FIGS. 6-7 illustrate flow charts of methods to maintain a temperature ofa data center according to examples; and

FIG. 8 illustrates a flow chart of a method to start a data centeraccording to an example.

DETAILED DESCRIPTION

In the following detailed description, reference is made to theaccompanying drawings which form a part hereof, and in which is depictedby way of illustration specific examples in which the present disclosuremay be practiced. It is to be understood that other examples may beutilized and structural or logical changes may be made without departingfrom the scope of the present disclosure.

Electronic system designs must balance conflicts between power density,spatial layout, temperature requirements, acoustic noise, and otherfactors. Air cooling systems typically use heat sinks and fans to removeheat from the system. The use of heat sinks and fans increase theelectrical power required to operate an electronic device in anelectronic system, and may cause excessive acoustic noise and lowersystem density. Liquid cooling can be more efficient than air cooling;however, the liquid cooling typically includes plumbing connectionswithin the electronic devices. As the liquid goes through the plumbingconnections the risk of leakage of liquid within the electronic deviceis introduced.

In examples, a control apparatus is provided. The control apparatusincludes a sensor module and a control module. The sensor module toreceive a measured environmental condition. The control module to usethe measured environmental condition to determine a fluid temperature tocool a first set of components and determine an air temperature to coola second set of components. The control apparatus provides a fluid orliquid cooling solution to enable the deployment of data centers in avariety of environments. The control apparatus provides an efficientcooling solution for racks that accommodate low to high power densities.

The phrase “environmental condition” refers to a measurable value in theair surrounding the electronic components, such as outdoor air, indoorair, or both. For example, an air temperature, a dry bulb temperature, awet bulb temperature, a dew point, a relative humidity, an altitude, apollution level, or a wind speed.

The phrase “electronic component” refers to a computing device such as aserver, blade server, server cartridge that provides computer solutions,storage solutions, network solutions and/or cloud services.

The phrase ‘modular data center’ refers to a data center withinterchangeable modules. For example, the modular data center mayinclude a performance optimized data center (POD), a collection of rackslike a modular cooling system (MCS), or a collection of warm watercooled racks like a supercomputer, or a high performance computing (HPC)cluster, that includes server modules, network solutions, and/or storagemodules.

FIG. 1 illustrates a block diagram of a system 100 to cool a modulardata center. The system 100 includes a fluid cooling device 140, an aircooling device 160, and a control apparatus 120. The fluid coolingdevice 140 to cool a first set of components of the modular data centerusing a fluid cooling loop. The air cooling device 160 to provide air tocool a second set of components of the modular data center. The controlapparatus 120 connected to the air cooling device 160 and the fluidcooling device 140 via, for example, a link 110.

The control apparatus 120 to determine an air cooling temperature forthe air cooling loop based on an environmental condition, and determinea fluid cooling temperature for the fluid cooling loop based on theenvironmental condition. The environmental condition may include, forexample, an air temperature and a relative humidity. For example, thecontrol apparatus 120 may include a control engine 122 and a sensorengine 128. The sensor engine 128 represents generally a combination ofhardware and/or programming to receive a measured environmentalcondition. The control engine 122 represents generally a combination ofhardware and/or programming to use the measured environmental condition,such as the air temperature and the relative humidity to determine thefluid cooling temperature to cool a first set of components and the aircooling temperature to cool a second set of components. The controlapparatus 120 to also transmit an air signal to the air cooling device160 to set the air cooling temperature, and transmit a fluid signal tothe fluid cooling device 140 to set the fluid cooling temperature. Forexample, the air signal and the fluid signal may be transmitted by thecontrol engine 122, the sensor engine 128, and/or an additional module,such as a communication module (not shown).

The link 110 may represent generally one or more of a cable, wireless,fiber optic, and/or remote connections via a telecommunication link, aninfrared link, a radio frequency link, or any other connectors orsystems that provide electronic communication. The link 110 may include,at least in part, an intranet, the Internet, or a combination of both.The link 110 may also include intermediate proxies, routers, switches,load balancers, and the like.

FIGS. 2-4 illustrate the system 100 of FIG. 1 according to examples.Referring to FIG. 2, a perspective view of the system 100 of FIG. 1 isillustrated according to the example. The system 100 includes a controlapparatus 120, the fluid cooling device 140, and the air cooling device160 connected to a modular data center 230. The modular data center 230as illustrated includes a rack 232, a set of electronic components ormodules 234 in the rack 232, a controller 236, and a power bus bar 238to deliver power to the racks. For example, the modular data center 230may include a performance optimized data center (POD), a collection ofracks like a modular cooling system (MCS), or a collection of warm watercooled racks like a supercomputer, or an HPC cluster, that includesserver modules, network solutions, and/or storage modules.

The control apparatus 120 may be connected to the data center 230 viathe controller 236. The controller 236 may be connected to theelectronic components, such as modules 234, i.e., server modules,storage modules, and/or network switches, and the rack 232. The controlapparatus 120, the fluid cooling device 140, and the air cooling device160 may be connected to one another and/or the modular data center 230via the link 110 that may include cables, wireless connection, fiberoptic connection, and/or other electronic connectors.

The control apparatus 120 determines an air cooling temperature based onan environmental condition, such as an air temperature and a relativehumidity, and determines a fluid cooling temperature based on theenvironmental condition, i.e. the air temperature and the relativehumidity. For example, the air temperature may be measured using an airtemperature sensor 222. The relative humidity may be measured using ahumidity sensor 224. The control apparatus 120 to also transmit an airsignal to the air cooling device 160 to set the air cooling temperature,and transmit a fluid signal to the fluid cooling device 140 to set thefluid cooling temperature. For example the air cooling temperature maybe set to thirty degrees Celsius and the fluid cooling temperature maybe set to forty degrees Celsius. The control apparatus 120 may updatethe air cooling temperature at predetermined intervals via the airsignal, and the control apparatus 120 may update the fluid coolingtemperature at predetermined intervals via the fluid signal. The updatesto the air cooling temperature and the fluid cooling temperature may bebased on new measurements of the environmental condition, such as theair temperature and the relative humidity obtained by the controlapparatus 120.

The control apparatus 120 may use the air temperature sensor 222 toobtain a measured air temperature and the humidity sensor 224 to obtaina measured relative humidity from an environment surrounding the system100, such as by measurement of weather or environmental conditionsoutside the data center and/or the air inside the data center. The airtemperature and the relative humidity may be received or obtained atpredetermined intervals to provide sufficient updates to the system 100.

Referring to FIGS. 2-3, the fluid cooling device 140 may include, forexample, an adiabatic fluid cooler (AFC) 240 that supplies water to coldplates that provide component level cooling, such as cooling of centralprocessing units (CPUs), dual in-line memory modules (DIMMs), and/orgraphics processing units (GPUs) using the fluid. By using the fluidcooling device 140 for a first set of components that provide a highheat load, such as the CPUs, DIMMs, and/or GPUs, a percentage of therack heat load may be managed and cooled using the fluid cooling device140. The actual percentage may be determined based on the environmentalconditions. For example, approximately seventy to ninety percent of therack heat load. The fluid may provide component level cooling, which,for example, allows rack heat to go directly to non chilled water andrelieves air flow for data centers and reduces the amount of air flowneeded. By using component-level cooling and by reducing the demand forair flow, a smaller air handier, such as a smaller DX unit 260, may beutilized. This can also eliminate the need for outside air, forinstance, in areas of high pollution. For example, the fluid may beprovided to the cold plates via a fluid supply 242 and returned to theAFC 240 via a fluid return 244. Component level cooling using a fluidrequires less power, which reserves more power for use by the electroniccomponents. The additional power for the electronic components providesthe ability to deploy racks and data centers with higher powerdensities. For example, power densities exceeding eighty kilowatts perrack in a chiller-less environment or where small amounts of mechanicalcooling through, for example, a DX unit 260, are beneficial, such as inhigh altitude areas where heat absorption by air cooling is reduced.Moreover, the system 100 with a chiller-less environment providesautonomous heat removal that does not require an external water coolingsystem.

The cross-sectional view of the system 100 of FIG. 1 is illustrated inFIG. 3 with the AFC 240 including a fluid supply 242 and the fluidreturn 244 to connect the AFC 240 to cold plates 346. For example, thecold plates 346 may be connected to DIMMs 331 and CPUs 333 to providecomponent level fluid cooling. The DIMMs 331 may further include DIMMcovers 332.

The fluid cooling device 140 is illustrated as an AFC 240 that providesor distributes the fluid to the components via the fluid supply 242. Forexample, the temperature of the fluid may be forty degrees Celsius. Thesystem's 100 ability to maintain a fluid temperature of forty degreesCelsius provides efficiency with cooling. The fluid supply 242 providesthe cold plates 346 with the fluid to cool the components bydistributing the fluid across or through the cold plates 346. The fluidthen carries the heat extracted from the components out of the coldplates 346 through the fluid return 244. The system 100 may furtherinclude fluid connectors for the fluid supply 242 and the fluid return244 to connect the fluid cooling device 140 to the electronic componentsor modules 234. The fluid may include water and/or other liquids, oils,or gases that may be used in a fluid loop to cool components.

The fluid return 244 returns the fluid to the AFC 240, which extractsthe heat from the water. For example, the AFC 240 is illustrated in FIG.3 to include a liquid to air heat exchanger 341 and a wet media 343. Thewet media 343 evaporatively cools the air before it passes over theliquid to air heat exchanger 341. The air-liquid heat exchanger mayinclude a condenser coil 365. For example, water may be dripped on amedia with air blowing over the water with fans 347 to cause the waterto evaporate and provide a cooler, more humid air. The wet media 343 mayalternatively be replaced with a cooler evaporative media. The fluid mayinclude for example, a loop that recycles the fluid and reuses the fluidto maintain a constant temperature of electronic components or modules234 and of the data center 230.

The air cooling device 160 is illustrated below the fluid cooling device140 in FIGS. 2-3. For example, the air cooling device 160 may include amechanical cooling device such as a direct expansion compressor-basedunit (DX) or chiller unit 260, The DX 260 may be positioned above a coldaisle 262 in the modular data center 230. The DX 260 may include directexpansion air handling units 361 and an evaporator coil 363 to provideair cooling to a second set of components. The fluid cooling device 140and the air cooling device 160 may share the wet media 343, thecondenser coil 365, and the fans 347.

For example, the DX 260 may provide air cooling for a small percentageof the components, such as the components that are not cooled using thefluid cooling device 140. For example, approximately ten to thirtypercent of the components may be cooled via air cooling; however, theactual percentage may be determined based on environmental conditions.The temperature of the air delivered may be, for example, thirty degreesCelsius. Moreover, the first set of components and the second set ofcomponents may be distinct groups of components. For example, the system100 may provide component-level fluid or liquid cooling for the devicesthat produce the most heat, such as CPUs, DIMMs, and GPUs, i.e., thefirst set of components, and air cooling for the balance of thecomponents, such as hard drives, power supplies, host bus adapters,supporting power regulation for CPU, GPU, and/or DIMMs and other boardrelated logic ASICs, i.e., the second set of components. Additionally,the component-level fluid or liquid cooling may be extended to coolother components, such as power supplies, network chips, and harddrives. However, the system 100 may also use both fluid cooling and aircooling on at least one of the same components, such that at least oneof the first set of the components and at least one of the second set ofcomponents are cooled using both air and fluid.

FIG. 4 illustrates a portion of the system 100 of FIG. 1. The controlengine 122 and the sensor engine 128 of the control apparatus 120 areillustrated linked 110 to a data store 480. The control engine 122functionalities are accomplished via the link 110 that connects thecontrol engine 122, the sensor engine 128, and the data store 480.

The data store 480 represents generally any memory configured to storedata accessible by the control engine 122 and/or the sensor engine 128in the performance of their functions. The data store 480 is, forexample, a database that stores, threshold environmental conditions 481,such as a threshold air temperature and a threshold relative humidity tocompare to measured air temperatures 482, measured relative humidity483, threshold data center temperatures 484, measured data centertemperatures 485, threshold fluid cooling temperatures 486, measuredfluid cooling temperatures 487, threshold air cooling temperatures 488,measured air cooling temperatures 489, and instructions 490 to performthe functions of the control engine 122 and the sensor engine 128.

The sensor engine 128 to send data to and receive data from a fluidcooling device 140 and an air cooling device 160 The sensor engine 128may also receive information regarding environmental conditions, such asthe air temperature outside a data center or the air temperature withinthe data center using sensors. For example, the sensor engine mayinclude temperature sensors, humidity sensors, pressure sensors, and/orflow sensors.

The control engine 122 to send data to and receive data from a fluidcooling device 140. The control engine 122 to manage a set of fluidcooling components. The set of fluid cooling components to cool the atleast one electronic component, such as CPUs, DIMMs, and/or GPUs. Forexample, the set of fluid cooling components may include a pump, anelectromechanical valve, a heat exchange loop, a leak detector, an airblower, louvers, and/or a sensor. The control engine 122 to also senddata to and receive data from an air cooling device 160. The air coolingdevice 160 to manage a set of air cooling components. The set of aircooling components to cool the second set of components, such as harddrives, power supplies, host bus adapters, supporting power regulationfor CPU, GPU, and/or DIMMs and other board related logic ASICs. The setof air cooling components may include a heat exchanger, a fan, a heatsink, and/or a sensor.

FIG. 5 illustrates a block diagram of a control apparatus 120 accordingto an example. The control apparatus 120 may include firmware or acomputer readable medium 500 that interfaces a fluid cooling device 140and an air cooling device 160. The control apparatus 120 is illustratedto include a memory 510, a processor 512, and an interface 530. Thememory 510 stores a set of instructions. The processor 512 is coupled tothe memory 510 to execute the set of instructions 490. The processor 512represents generally any processor configured to execute programinstructions stored in memory 510 to perform various specifiedfunctions. The interface 530 represents generally any interface enablingthe control apparatus 120 to communicate with the control engine 122,the sensor engine 128, and/or the data store 480 via the link 110, asillustrated in FIG. 5.

The memory 510 is illustrated to include an operating system 520 andapplications 540, The operating system 520 represents a collection ofprograms that when executed by the processor 512 serves as a platform onwhich applications 540 run. Examples of operating systems 520 includevarious versions of Microsoft's Windows® and Linux®. Applications 540represent program instructions that when executed by the processor 512function as an application that when executed by a processor 512 controlthe fluid cooling device 140 and the air cooling device 160.

For example, FIG. 5 illustrates a control module 522 and a sensor module528 as executable program instructions stored in memory 510 of thecontrol apparatus 120. The sensor module 528, when executed, receives ameasured environmental condition, both of which may be used to determinethe fluid temperature and the air temperature.

The control module 522, when executed determines an air coolingtemperature and a fluid cooling temperature based on the environmentalcondition, such as the air temperature and the relative humidity. Thecontrol module 522 and/or the sensor module 528 may transmit a fluidsignal and an air signal to set the fluid cooling temperature and theair cooling temperature. For example, the set of instructions enable thecontrol engine 122 and/or the sensor engine 128 to communicate with thefluid cooling device 140 to set the fluid temperature and communicatewith the air cooling device 160 to set the air temperature. The controlmodule 522 may also determine a flow rate for an air loop thatcirculates the air temperature and a fluid loop that circulates thefluid temperature. Additional considerations incorporated into theinstructions may include adjusting the air temperature, the fluidtemperature, and/or the flow rates for the air loop and the fluid loopbased on a work load. For example, the control module 522 may furtherinclude a workload value to adjust the fluid temperature and the airtemperature based on a workload.

The set of instructions 490 facilitate the transmission of data to,from, and between the control module 522 and the sensor module 528. Forexample, the set of instructions 490 are executed to send data andreceive data, such as threshold environmental conditions 481, i.e., athreshold air temperature, a threshold relative humidity, a thresholdwet bulb temperature, a threshold dry bulb temperature, a threshold dewpoint, a threshold altitude, threshold pollution level and/or athreshold wind speed; measured environmental conditions, such asmeasured air temperatures 482, measured relative humidity 483; thresholddata center temperatures 484, measured data center temperatures 485,threshold fluid cooling temperatures 486, measured fluid coolingtemperatures 487, threshold air cooling temperatures 488, measured aircooling temperatures 489. In an example, the control module 522 mayanalyze the measured air temperatures 482, measured relative humidity483, measured data center temperatures 485, measured fluid coolingtemperatures 487, and/or measure air cooling temperatures 489 and basedon the data determine a fluid cooling temperature for the fluid coolingloop and an air cooling temperature. The information related to thefluid cooling temperature and the air cooling temperature may then becommunicated to the fluid cooling device 140 and/or the air coolingdevice 160 via the control module 522 and/or sensor module 528. Theinformation may be communicated via a signal transmission to the fluidcooling device 140 and/or the air coaling device 160 and the informationmay be in the form of a setting, an adjustment to the fluid coalingdevice 140 and/or the air cooling device 160.

Referring back to FIG. 1, the control engine 122 and the sensor engine128 of the control apparatus 120 are described as combinations ofhardware and/or programming. As illustrated in FIG. 5, the hardwareportions include the processor 512. The programming portions include theoperating system 520, applications 540, and/or combinations thereof. Forexample, the control module 522 represents program instructions 490 thatwhen executed by a processor 512 cause the implementation of the of thecontrol engine 122. The sensor module 528 represents programinstructions 490 that when executed by a processor 512 cause theimplementation of the sensor engine 128.

The programming of the control module 522 and sensor module 528 may beprocessor 512 executable instructions stored on a memory 510 thatincludes a tangible memory media and the hardware includes a processor512 to execute the instructions. The memory 510 may store programinstructions that when executed by the processor 512 cause the processor512 to perform the program instructions. The memory 510 is integrated inthe same device (or system) as the processor 512 or it is separate butaccessible to that device (or system) and processor 512.

In some examples, the program instructions may be part of aninstallation package that can be executed by the processor 512 toperform a method using the system 100. The memory 510 is a portablemedium such as a CD, DVD, or flash drive or a memory maintained by aserver from which the installation package can be downloaded andinstalled. In some examples, the program instructions may be part of anapplication or applications already installed on a computing device. Infurther examples, the memory 510 includes integrated memory, such as ahard drive.

FIGS. 6-7 illustrate flow charts of methods to maintain a temperature ofa data center according to examples. Referring to FIG. 6, a method 600to cool a modular data center is provided. The method 600 obtains anenvironmental condition using a sensing device in block 620. Forexample, the environmental condition may include the air temperature andthe relative humidity, which may be used to determine a wet bulbtemperature. In block 640, a fluid is distributed at a fluid coolingtemperature via a component-level fluid cooling device to remove a firstportion of a rack heat load. The fluid cooling temperature may bedetermined by the control apparatus based on the comparison of athreshold environmental condition and a measured environmentalcondition. Air is circulated at an air cooling temperature by an aircooling device to cool a second portion of the rack heat load in block660. The air cooling temperature may be provided by a control apparatusand determined based on the comparison of the threshold environmentalcondition and the measured environmental condition.

The fluid cooling temperature, the air cooling temperature, and/or flowrates may also be adjusted based on a variety of factors. For example,workload information may be manually entered through an input device ordetermined based on the operation and functions within the data center.Moreover, adjustments may be made to manual entry to environmentalconditions, for example, if a sudden change in the environmentalconditions or weather is expected, manual adjustments may be made toadjust the control of the data center preemptively. Furthermore,adjustments may be made manually or automatically to adjust the air andfluid levels. For example, the amount of heat the air is exposed to maybe adjusted. Other adjustments may be made in response to power suppliesand energy considerations. The adjustments may be further made toinfluence the control apparatus' functionality by modifying thedeterminations made for the air cooling device and the fluid coolingdevice and/or override the determinations of the control apparatus.These adjustments whether made automatically or manually, may impact thestart-up, the operation, and/or the shutdown of the system.

The method 600 may further include dynamically measuring and updatingthe air temperature and the fluid temperature as illustrated in the flowchart 700 of FIG. 7. For example, a measured wet bulb temperature may becompared to a threshold wet bulb in block 710. If the measured wet bulbtemperature is greater than the threshold wet bulb temperature, the aircooling temperature is set to a determined air temperature, such astwenty-five degrees Celsius; and the fluid cooling temperature is set toa determined fluid cooling temperature, such as thirty degrees Celsius,as illustrated in block 720.

Else, if the measured wet bulb temperature is less than or equal to thethreshold wet bulb temperature, the flow chart moves to block 730. Inblock 730, the temperature of the fluid in the AFC and the air in thecold aisle is analyzed. In block 740, a measured fluid temperature iscompared to a fluid temperature threshold. For example, if the measuredfluid temperature is less than or equal to thirty degrees Celsius goback to block 710. If the measure fluid temperature is greater thanthirty degrees Celsius, then adjust the AFC in block 750. The AFC may beadjusted by first setting a water flow rate for the evaporative coolingand the flow rate through the heat exchanger. Next, set the water bypasspast the heat exchanger and set the blower speed. Then, re-measure themeasured fluid temperature and repeat any of the above steps.

In block, 760, the measured air temperature is compared to an airtemperature threshold. For example, if the measured air temperature isless than or equal to thirty-five degrees Celsius, go back to block 710.If the measured air temperature is greater than thirty-five degreesCelsius, then adjust the DX in block 770. The DX may be adjusted bysetting a compressor speed, setting a hot gas bypass, setting acondenser blower speed, and/or setting a cold aisle blower speed.Thereafter, the cold aisle air temperature and pressure may be measuredand the adjustments to the DX may be repeated. Finally, go back to block710 and repeat at predefined intervals, such as once an hour, once everytwenty minutes, or continuously.

FIG. 8 illustrates a flow chart 800 of a method to start a data centeraccording to an example. The method includes evaluating theenvironmental conditions surrounding the data center to determine astart-up sequence. Referring to FIG. 8, block 810 compares thetemperature of the air in the data center. For example, if thetemperature of the air is greater than or equal to a thresholdtemperature, such as ten degrees Celsius, the data center may be startednormally, as indicated in block 820. However, if the temperature of theair is less than ten degrees Celsius, block 830 determines if the airtemperature has been less than ten degrees Celsius for more than apredetermined number of hours, for example twelve hours. If the airtemperature has not been below ten degrees Celsius for more than thepredetermined number of hours, then the data center may be startednormally, as indicated in block 840. If the temperature of the air isless than ten degrees Celsius for more than the predetermined number ofhours, then a modified start-up is initiated as illustrated in the loop850.

To initiate the AFC start-up operation, which includes running the waterpumps may be run and the inline water heaters may be run as needed,while letting the evaporator cooler remain off, as illustrated in block860. The AFC start-up operation may be set to maintain the fluid at tendegrees Celsius. The DX start-up operation is illustrated in block 870.The DX start-up includes running the cold aisle blowers and the heaterswhen the temperature of the air is less than ten degrees Celsius and notclose to ten degrees Celsius. When the temperature of the air is closeto ten degrees Celsius, the heaters do not need to be run, The DXstart-up operation may be set to maintain the fluid at thirty-fivedegrees Celsius.

The temperature of the data center may be checked during the start-uploop 850, if the data center remains below ten degrees Celsius, then theloop 850 continues with blocks 860 and 870 and the data center is notpowered up. In block 880, the temperature of the data center and theelectronic components are evaluated. Once the data center and electroniccomponents reach ten degrees Celsius, the AFC and DX, may be runnormally and the data center and electronic components may bepowered'up, as illustrated in block 890.

Although the flow diagram of FIGS. 6-8 illustrate specific orders ofexecution, the order of execution may differ from that which isillustrated. For example, the order of execution of the blocks may bescrambled relative to the order shown. Also, the blocks shown insuccession may be executed concurrently or with partial concurrence. Allsuch variations are within the scope of the present disclosure.

The present disclosure has been described using non-limiting detaileddescriptions of examples thereof and is not intended to limit the scopeof the present disclosure. It should be understood that features and/oroperations described with respect to one example may be used with otherexamples and that not all examples of the present disclosure have all ofthe features and/or operations illustrated in a particular figure ordescribed with respect to one of the examples. Variations of examplesdescribed will occur to persons of the art. Furthermore, the terms“comprise,” “include,” “have” and their conjugates, shall mean, whenused in the present disclosure and/or claims, “including but notnecessarily limited to.”

It is noted that some of the above described examples may includestructure, acts or details of structures and acts that may not beessential to the present disclosure and are intended to be exemplary.Structure and acts described herein are replaceable by equivalents,which perform the same function, even if the structure or acts aredifferent, as known in the art. Therefore, the scope of the presentdisclosure is limited only by the elements and limitations as used inthe claims.

What is claimed is:
 1. A system to cool a modular data centercomprising: a fluid cooling device to cool a first set of components ofthe modular data center using a fluid cooling loop; an air coolingdevice to provide an air to cool a second set of components of themodular data center; and a control apparatus to: determine an aircooling temperature for the air cooling loop based on an environmentalcondition; determine a fluid cooling temperature for the fluid coolingloop based on the environmental condition; transmit an air signal to theair cooling device to set he air cooling temperature, and transmit afluid signal to the fluid cooling device to set the fluid coolingtemperature
 2. The system of claim 1, wherein the air cooling devicecomprises a direct expansion compressor-based unit
 3. The system ofclaim 1, wherein the fluid cooling device comprises an adiabatic fluidcooler.
 4. The system of claim 1, wherein the environmental conditionincludes at least one measured environmental condition selected from thefollowing: an air temperature, a relative humidity, a dew point, a wetbulb temperature, a dry bulb temperature, an altitude, a pollutionlevel, and a wind speed.
 5. The system of claim 1, wherein the controlapparatus updates the air signal and the fluid signal at predeterminedintervals.
 6. The system of claim 1, wherein the control apparatusdetermines the fluid cooling temperature and the air cooling temperaturebased on a comparison of a threshold environmental condition and ameasured environmental condition.
 7. The system of claim 1, wherein thefluid cooling device cools at least one component selected from acentral processing unit, a graphics processing unit, a dual in-linememory module, a power supply, a network chip, and a hard drive.
 8. Acontrol apparatus comprising: a sensor module to receive a measuredenvironmental condition; and a control module to use the measuredenvironmental condition to: determine a fluid temperature to cool afirst set of components; and determine an air temperature to cool asecond set of components.
 9. The control apparatus of claim 8, whereinthe control module further includes a workload value to adjust the fluidtemperature and the air temperature based on a workload.
 10. The controlapparatus of claim 8, wherein the sensor module comprises a humiditysensor to obtain the measured relative humidity.
 11. The controlapparatus of claim 8, wherein the sensor module receives theenvironmental condition at predetermined intervals.
 12. The controlapparatus of claim 8, wherein the control module determines a flow ratefor an air loop that circulates the air temperature and a fluid loopthat circulates the fluid temperature.
 13. A method to cool a modulardata center comprising: obtaining an environmental condition using asensing device; distributing a fluid at a fluid cooling temperature witha component level fluid cooling device to remove a first portion of arack heat load, the fluid cooling temperature based on the environmentalcondition; and circulating air at an air cooling temperature with an aircooling device to cool a second portion of the rack heat load, the aircooling temperature based on the air temperature and the relativehumidity.
 14. The method of claim 13, further comprising dynamicallymeasuring and updating the environmental condition.
 15. The method ofclaim 13, further comprising evaluating an environment surrounding adata center to determine a start-up sequence.